Process for producing preservable squeezed vegetable juice

ABSTRACT

A process for preparing storable vegetable juice comprising crushing vegetables to extract juice, adding an organic acid to the vegetable juice, and treating this vegetable juice with a weakly basic anion exchange resin on which an organic acid has previously been adsorbed and a food containing a vegetable juice prepared by the process. The process can produce vegetable juice which can be stored at room temperature, produces no bad odor when stored at room temperature, and is free from a resin odor which has been unavoidable when a weakly basic anion exchange resin was used.

FIELD OF TECHNOLOGY

The present invention relates to a process for preparing storablevegetable juice and, more particularly, to a process for preparingstorable vegetable juice which not only produces almost no odor whenstored at room temperature, but also is free from a resin odororiginating from a weakly basic anion exchange resin.

BACKGROUND ART

Along with increased health consciousness among consumers in recentyears, the desire for vegetable drinks which can be easily consumed isgrowing.

However, presently available vegetable drinks are a mixed tomato juicemade from about 90% tomato and about 10% other vegetables, a mixed juicemade from vegetables which are comparatively odorless, such as carrotand spinach, and a major portion of fruit juice, and the like. With theexception of tomato juice and carrot juice, there are no vegetablejuices which are true vegetable juices commercially available at thepresent time.

When a juice extracted from some vegetables belonging to the Brassicafamily, such as cabbage, broccoli, Brussels sprouts, cauliflower, andkohlrabi, which are reported to exhibit the capability of preventingcancerous growth, or other vegetables, such as radish, onion, or eggplant, is provided as a drink, as is, or mixed with a fruit juice, thisjuice produces a distinct odor when stored at room temperature. Such ajuice cannot be used as a raw material for manufacturing canned juice orproducts aseptically filled in paper receptacles to be distributed atroom temperatures.

The inventors of the present invention have previously found that avegetable juice at close to a neutral pH with no objectionable vegetableor other unusual odor can be produced by adding an edible acid such asan organic acid to vegetable juice and treating this juice with anweakly basic anion exchange resin by a batch method or circulating thejuice through a column packed with a weakly basic anion exchange resin.The inventors found that the resulting juice is suitable as a rawmaterial for producing drinks which can be stored at high temperatures.The inventors then filed a patent application (Japanese PatentApplication Laid-open No. 79351/1995).

However, because the weakly basic anion exchange resin used in thismethod contains amine as an active group, the treatment of vegetablejuice with this resin easily causes imperfect binding sites of the amineto be exposed and to shift into the recovered fluid, leaving anunpleasant odor which is called an objectionable resin odor.

Although it is possible to kill this unpleasant odor to "a degree thatthis resin odor is not specifically noticed" by diluting the treatedvegetable juice to produce a drink with a vegetable juice concentrationof about 10-20%, by mixing the vegetable juice with a fruit juice, or byadding a perfume possessing an aroma which exceeds this objectionableresin odor, incorporation of an amine compound in food is not desirablefrom the viewpoint of food hygiene. Improvements in this method aretherefore desired.

Accordingly, the development of a process for preparing vegetable juicewithout an amine odor due to a weakly basic anion exchange resin whileutilizing the superior odor removal action of this resin has beendesired. An object of the present invention is to provide a vegetablejuice overcoming the problems in conventional vegetable juices.

DISCLOSURE OF THE INVENTION

The inventors of the present invention have conducted extensive studieson the method for preventing the amine odor caused by the weakly basicanion exchange resin in the processing of vegetable juice. As a result,the inventors found that the amine odor can be effectively prevented ifa weakly basic anion exchange resin is treated with an organic acidprior to processing the vegetable juice. This finding has led to thecompletion of the present invention.

Accordingly, the present invention relates to a process for preparingstorable vegetable juice comprising crushing the vegetables to extractthe juice, adding an organic acid to the vegetable juice, and treatingthis vegetable juice with a weakly basic anion exchange resin on whichan organic acid has previously been adsorbed.

BEST MODE FOR CARRYING OUT THE INVENTION

The weakly basic anion exchange resin on which an organic acid haspreviously been adsorbed used in the present invention (hereinafterreferred to as "organic acid-adsorbing resin") can be prepared, forexample, by passing a solution of an organic acid, such as citric acid,malic acid, tartaric acid, lactic acid, or L-ascorbic acid, through aweakly basic anion exchange resin, e.g. a porous weakly basic anionexchange resin used for demineralization or deoxidation, thereby causingthe organic acid to be adsorbed on the weakly basic anion exchangeresin, then washing the resin with water.

Diaion™ WA20, WA21, WA30, Amberlite™ IRA-93ZU, and the like are given asexamples of the weakly basic anion exchange resin on which the organicacid is adsorbed. Preferred weakly basic anion exchange resins from theviewpoint of resistance to acids used for regeneration of the resin areAmberlite™ IRA94S and Amberlite™ IRA-94S-HG (manufactured by JapanOrgano Co., Ltd.).

The amount of the organic acid to be adsorbed on this weakly basic anionexchange resin is preferably in the range of about 2 to 3 equivalents ofthe amount of resin.

Specifically, a solution of the organic acid with a concentration of 2to 3 equivalents g/1000 ml is fed through 1 BV (Bed Volume: the volumeof resin) of resin. It is possible to feed a more dilute solution in theamount of 1 BV times the magnification dilution, but the addition of anexcess amount of organic acid is undesirable because this may delay thesubsequent step for washing with water.

Washing the organic acid-adsorbing resin with water is carried out tosufficiently remove the effluent water containing a high concentrationof a substance with a very unpleasant resin odor. This unpleasant resinodor is thought to be produced by desorption of an incomplete bindingsubstance of an amine-type active group from the weakly basic anionexchange resin together with the organic acid, partly due to swelling ofresin on the acidic side.

Because the organic acid existing in the weakly basic anion exchangeresin cannot easily be excluded due to its inherent properties, thisunpleasant odor must be removed by washing with a large amount of water.The amount of water used for washing should be 10 times, preferably 14times, and more preferably 16 times, the amount of the resin. Whetherthe washing is sufficient or not can be confirmed by checking the odorof the effluent water or by measuring the acidity of the organic acid orthe pH of the effluent water.

When the acidity is used to confirm the completeness of washing, theacidity of the adsorbed organic acid in the effluent water is measured.Washing is deemed to be complete when the acidity is 0.2% or less,preferably 0.1% or less. Acidity as used here is defined as the weightpercent of the organic acid contained in 100 g of the sample (theeffluent water). When pH is used as the measure for checkingcompleteness of washing, washing is deemed to be complete when the pH is2.6 or more, and preferably 2.8 or more.

As the water used for washing, common drinking water such as well water,city water, and the like can be used. When the hardness of the water ishigh, the water is desirably softened by removing calcium and the like.Although demineralized water is ideal for washing, it is desirable inview of economy to first wash with a large amount of common water andthen with demineralized water in the amount of about 2BV.

Since imperfectly combined active groups in the resin may be exposedover time after the treatment, the adsorption of organic acid on theweakly basic anion exchange resin and the washing are preferably carriedout the same day or the day previous to vegetable juice processing.

Next, the method for treating vegetable juice with the organicacid-adsorbing resin which was obtained by the above process will beexplained.

The vegetable juice used in the present invention may be obtained bybranching, crushing, and extraction of vegetables by a conventionalmethod or obtained by a low temperature extraction of vegetables. It isdesirable that the juice be prepared by crushing and extraction at a lowtemperature in the presence of ascorbic acid, followed by heating todeactivate biological enzymes. Juice with excellent taste and flavor canbe obtained by preparing the vegetable juice in this manner. Theconcentration of the ascorbic acid added to the vegetable when juice isextracted is preferably in the range of 60 to 200 mg %.

An organic acid such as citric acid, malic acid, tartaric acid, lacticacid, or L-ascorbic acid is then added to the vegetable juice thusprepared.

A fresh vegetable juice immediately after extraction is almost neutralwith a pH in the neighborhood of 6.0. It is desirable to add the organicacid in an amount sufficient to change the pH of the vegetable juice toabout 3.0 to 4.5, preferably about 3.5 to 4.0. A pH of 4.5 or more isundesirable because the vegetable juice deteriorates easily. If the pHis less than 3.0, on the other hand, not only is it difficult to handlethe juice as food, but also the juice may produce an additional resinodor, particularly when the pH of the vegetable juice is lower than theresin pH. The resin pH here means the pH of the effluent water.

The vegetable juice to which the organic acid has been added asmentioned above is then subjected to treatment with the organicacid-adsorbing resin which had been prepared according to the methodpreviously described.

This treatment with the resin may be carried out either by a so-calledbatch method or a semi-continuous method which may be partly a batchmethod comprising causing a meshed basket with the resin placed thereinto move up and down in a tank filled with the juice. These methods maybe applied to the manufacture of a small amount of vegetable juice. Acontinuous process using a column ion exchange method is moreadvantageous when regeneration of the resin and continuous, energysaving, mass production is taken into account.

The treatment of vegetable juice with the organic acid-adsorbing resinwill now be described more specifically with respect to the continuousprocess using the column ion exchange method as an example.

First of all, a prescribed amount of the organic acid-absorbing resinprepared by the above-described method is filled into a column. Forexample, 10 to 100 parts of the extracted vegetable juice. As required,it is possible to use an organic acid-absorbing resin prepared in thecolumn according to the above-described method, that is, by filling aprescribed amount of weakly basic anion exchange resin into a column,causing this resin to adsorb an organic acid, and washing the resin.

Although the amount of the resin filled into the column varies accordingto the concentration of the vegetable juice to be processed, about 10-30parts by volume, preferably about 15-25 parts by volume, of the resinfor 100 parts by volume of the vegetable juice may be used, when astraight vegetable juice (e.g. in the case of cabbage juice, Brigg'ssugar degree (hereinafter abbreviated as "Bx") of 5) is used.

It is possible to provide a previously concentrated vegetable juice, andto carry out extraction of the juice and treatment of the juice withresin at different times. This ensures a decrease in the cost of storingthe vegetable juice and minimizing the capacities of tanks and auxiliaryfacilities.

In this instance, the vegetable juice obtained in the previous step isfrozen for storage. The frozen juice is thawed before treatment with theresin. Although this procedure may increase the concentration of thevegetable juice to be processed, the amount of resin can beappropriately determined according to the Bx of the vegetable juice,because the Bx of vegetable juice should be proportionate to the amountof resin used. For example, if the Bx of a cabbage juice is 10, theamount of resin should be twice the amount mentioned above; if the Bx is15, the amount of resin should be three times.

Taking into account the effect of viscosity, the efficiency ofassociated equipment such as tanks, and the recovery ratio, and thelike, ideal conditions to ensure easy processing in the concentration ofthe above-mentioned vegetable juice is about 15 Bx (about 60 parts ofresin for 100 parts of vegetable juice). Because an organic acid isadded to the vegetable juice before processing, the pH is desirably inthe range of 3.5-4.0 without regard to the concentration.

In the treatment of the vegetable juice or its concentrate with theorganic acid-absorbing resin, the feed rate of the vegetable juice tothe organic acid-absorbing resin column, in terms of space velocity(SV), is about SV=2-20 BV/h, which means that vegetable juice of avolume equivalent to the resin is fed to the column in 3 to 30 minutes,and preferably about SV=8-10 BV/h.

When feeding of the vegetable juice is started, the eluate from thecolumn initially contains water. Water comes in even at the completionof the extraction process. The timing of recovery should therefore bedecided taking the economy in terms of yield and the concentration ofthe finished product into consideration.

The total amount of vegetable juice processed by a unit volume of resinis selected taking into account characteristics expected of the targetvegetable juice such as resistance to high temperature storage.

It should be noted that the above-described amount of vegetable juice tobe processed by a unit volume of resin and the volume of resin to theamount of vegetable juice are given as a standard indication. Withregard to a cabbage juice with the Bx of about 15, when the treatedamount of vegetable juice exceeds three parts by volume for one part byvolume of resin, a vegetable odor begins to remain in the resultingvegetable juice and it becomes difficult to produce a vegetable juicewith excellent storage stability at high temperatures.

However, there is no resin odor at all, even if the above-describedvegetable juice with a Bx of about 15 is processed up to an amount of 10times the volume of the resin. In addition, because a vegetable juicewith a pH of about 4.0 before treatment is recovered as a juice with apH of about 4.1 to 4.5, these conditions are very advantageous forcombating microorganisms during treatment. Although it is possible toobtain the juice as a product or a raw material for a product as is, thejuice is preferably filtered to remove resin chips and the like whichmay be present. As required, the juice may be further concentrated.

In addition, to prevent deterioration during storage β-cyclodextrin maybe dissolved in an amount of 0.1 to 0.5% straight concentrationvegetable juice (Bx 5).

Moreover, it is also effective for preventing deterioration to dissolvesodium chloride in an amount of 0.08 to 0.3% in a straight concentrationvegetable juice (Bx 5).

The vegetable juice of the present invention thus obtained containsalmost all effective components, such as ascorbic acid and amine-typenitrogen components, which are contained in the vegetable juice beforeprocessing by low temperature extraction and the resin treatment.

It is desirable to obtain the vegetable juice of the present inventionas a transparent juice. To obtain the transparent vegetable juice, atleast one treatment to make the juice transparent must be carried out ineither step of the process, particularly preferably prior to the resintreatment step. This treatment for preparing transparent juicecomprises, for example, adding an organic acid to the vegetable juiceproduced by crushing and extraction to accelerate precipitation ofsuspensions, and treating the juice with an enzyme such as pectinase.Treatment with an UF membrane is another example of a method forpreparing a transparent vegetable juice.

In the above method for preparing a transparent vegetable juice, aconventional filtration method is suitably employed as a post-treatmentafter treatment with an enzyme such as pectinase. The enzyme used can bedeactivated by heat treatment at 85° C. or higher. Enzyme treatment of avegetable juice with a low pH produced by the addition of an organicacid, followed by heat treatment to deactivate the enzyme isparticularly effective to promote secondary precipitation of proteins.The protein precipitates thus produced can be removed by centrifugation,filtration using kieselguhr, or the like.

The weakly basic anion exchange resin used for treating the vegetablejuice can be regenerated for repeated use.

The regeneration can preferably be carried out in the order of alkaliwashing, acid washing, and alkali washing. Completion of regenerationcan be confirmed by the absence of odor, the pH of the effluent water,and the absence of phenolphthalein color in the effluent water.

The vegetable juice of the present invention can be served as a drink asis, or optionally after the addition of various additives to adjusttaste or flavor, such as salt (sodium chloride), a sweetener such assugar, a sour tasting additive, a perfume, and a preservative. A stepfor the addition of these additives may be provided in the process ofthe present invention. Moreover, it is also possible to prepare a mixedjuice by blending the vegetable juice with a transparent or opaque fruitjuice.

Beside drinks, the vegetable juice of the present invention can be usedfor preparing vegetable jelly, vegetable-containing yoghurt, vegetablepudding, jam, and the like by blending with a thickner or a gelationpolysaccharide, such as pectin, agar, or carrageen, fermented milk, eggyolk, and the like. It is also possible to use the vegetable juice infoods such as gum drop, chocolate, bread, candy, and the like.

Although the mechanism whereby vegetable juice with excellent storagestability and minimum change in the flavor can be obtained by theprocess of the present invention is not known, it is understood that theprocess for causing the weakly basic anion exchange resin to adsorb anorganic acid, followed by sufficiently washing with water, completelyremoves amines imperfectly combined with the resin, which are consideredto be the cause of the resin odor. As a result, the vegetable juice isnot contaminated with such imperfectly combined amines even if the juiceis treated with the resin after the addition of an organic acid. This isthought to be the reason that the vegetable juice of the presentinvention is free from a resin odor.

In addition, the organic acid adsorbed by the weakly basic anionexchange resin and the organic acid added to the vegetable juice mayproduce a new cross-linked material on the surface of the resin. Thiscross-linked material is believed to adsorb odorous substances or theirprecursors which may cause the unpleasant odor, thereby producingvegetable juice storable at room temperature.

Heretofore, a sourness reducing treatment for summer tangerines or grapefruit has been known as an application of a weakly basic anion exchangeresin to juice. This resin is used in this method to reduce the acidityof fruit juice. There have been no suggestions relating to removal ofunpleasant odorous components.

A process for decreasing the content of nitric acid ion in vegetablejuice after treatment with a weakly basic anion exchange resin is alsoknown ("Process for manufacturing carrot juice", Japanese PatentApplication Laid-open No. 31678/1984). The inventor of this patentdescribes that a "treatment to remove about 60-70% of nitric acid ion isdesirable for preventing a decrease in the flavor of the carrot juice",implying that the treatment with the weakly basic anion exchange resinto reduce nitric acid ion may have something to do with a decrease inflavor. The inventor further states in the examples that "there is nodifference in flavor between the method of the invention and theconventional method". The object of this patent is thus the removal ofnitric acid ion components and it is clear that the patent does notsuggest anything about removal of unpleasant odors.

An example of the method for treating juice with the other ion exchangeresin relates to a process for removing s-methyl methionine sulfoniumwhich is a precursor of an odorous substance produced when juice fromWenzhou tangerine is heated. According to this process the s-methylmethionine sulfonium is removed by an acidic cation-exchange resin(Osashima Yutaka et al., "Removal of s-methyl methionine sulfonium inWenzhou tangerine juice", Journal of Agricultural Chemistry Association,Vol. 59, No.5 (1985)). Another example relates to a method formanufacturing high-quality vegetable juice by treating a vegetable juicewith a cation exchange resin (Method For Manufacturing Vegetable Juice,Japanese Patent Application Laid-open No. 56711/1993). The both methodsemploy an acidic cation-exchange resin and neither suggests the use of aweakly basic anion exchange resin, particularly the use of the weaklybasic anion exchange resin treated with an organic acid of the presentinvention.

A method for causing a basic resin to adsorb a complex salt and thencausing the resin to adsorb an ion as a complex salt is known in theart. A typical example is a method comprising causing a basic resin toadsorb citric acid, then causing the resin to adsorb a polyvalent ionsuch as Fe, Al, or V as a complex salt to separate these polyvalent ionsfrom alkali metals (for example, Mitsubishi Kasei Technical ServiceSeries, Diaion Ion Exchange Resin-Synthetic Adsorbent, Manual II!, p35˜). This method is industrially applied to the removal of metal ionsin the purification of hydrochloric acid.

The relationship between removal of the components producing unpleasantodor according to the present invention and the removal of metalsaccording to this prior art technology is quite unknown. There has beenno example showing application of this method to the food industry.Clearly, no suggestions were given as far as a relationship with thepresent invention is concerned.

Accordingly, it is clear that the storable vegetable juice of thepresent invention is not based on any conventionally known actions ofion exchange resins. The present invention is thus believed to be basedon a new mechanism which is quite different from any known actions ofion exchange resins.

Other features of the invention will become apparent in the course ofthe following description of the exemplary embodiments which are givenfor illustration of the invention and are not intended to be limitingthereof.

EXAMPLES Example 1

(1) The cores of a cabbage was removed and the cabbage was cut with acutter crosswise into four equal fractions. The leaves of the cabbagewere separated and washed with a detergent suitable for use with foods.After rinsing to remove the detergent the leaves were immersed in a 0.3%ascorbic acid solution for 3 minutes.

The leaves were then crushed while pouring a 1.5% ascorbic acid solutionin the amount of one part to 9 parts of the cabbage using amicro-grader. Juice was extracted from the crushed cabbage using aVetter-type screw press. The collected juice was heated for 10 secondsat 110° C., thus obtaining a crude cabbage juice with a pH of 5.7containing ascorbic acid at a concentration of 105 mg %.

(2) A 0.25% citric acid solution was added to the crude cabbage juicethus obtained to confirm the pH was about 4.0. After the addition ofPectinase SS™ (manufactured by Yakult Pharmaceutical Industry Co., Ltd.)to make a concentration of 0.05%, an enzymatic reaction was carried outat 45° C. for one hour. After the enzymatic reaction, the resultantmixture was heated at 95° C. for 10 seconds, quenched, and subjected toa DeLaval centrifuge separator to remove suspensions. The mother liquorwas filtered through #200 kieselguhr and concentrated under vacuum to 30Bx.

(3) A weakly basic anion exchange resin, IRA-94S™ was filled into acolumn (the resin volume: 1000 l). An organic acid (citric acid) wasadsorbed on the resin by causing 1N citric acid in the amount of 3 BV topass through the column. The resin was then washed with 18 BV of ionexchanged water. The organic acid treated resin in this column had a pHof 2.82 and contained citric acid at a concentration of acid degree of0.08%.

(4) The vegetable juice obtained in (2) above was diluted to 15° Bx toobtain a vegetable juice for treatment (ascorbic acid content: 310 mg %,3.99 pH, acid degree of citric acid: 1.3%). 2000 l of this vegetablejuice was passed downward through the organic acid-treated columnprepared in (3) above at a space velocity of SV=10 and a flow rate of1000 l/6 minutes.

(5) To avoid dilution of the vegetable juice when switching to water,vegetable juice collected during 5 minutes from the start of elution and5 minutes from the start of water feeding after the treatment wasrejected.

1930 l of vegetable juice (recovered juice) at 14.4 Bx and 4.3 pH wasthus obtained.

(6) Regeneration and washing of the organic acid-treated resin IRA-94S™in the column used in (4) above were carried out as follows.

Specifically, particularly to wash out coloring matters first of all,normal water in the amount of 2 BV or more, followed by 1N solution ofNaOH in an amount of 2.5 BV at a space velocity of about SV=10, werepassed through the column after the treatment in (5) above. Then, afterwashing with ion exchange water in the amount of 5 BV or more, a 1Nsolution of hydrochloric acid in the amount of 2.5 BV was fed to thecolumn at a space velocity of about SV=10. The column was again washedwith ion exchange water in the amount of 5 BV or more, treated with a 1N solution of NaOH in the amount of 2.5 BV at about SV=10, then finallywashed with ion exchange water in the amount of 5 BV or more.

This second alkali washing was carried out to return the resin to itsbasic (alkaline) state and to cause the coloring matter which was notremoved in the first alkali washing to come into contact with the alkalisolution due to swelling of the resin by the acid treatment, therebyensuring more effective washing (the resin may shrink under alkalineconditions, so that one alkali washing may not completely removecoloring matter)

Example 2

0.5 part of β-cyclodextrin was added to 100 parts of the vegetable juice(14.3 Bx) obtained in Example 1 and the mixture was stirred for 20minutes to dissolve the β-cyclodextrin in the vegetable juice.

Example 3

(1) The core of a cabbage was removed and the cabbage was cut with acutter crosswise into four equal fractions. The leaves of the cabbagewere separated and washed with a detergent suitable for food use. Afterrinsing with water, the leaves were treated with hot water to heat thecenter of thickest ribs to 85° C.

The leaves were then crushed using a micro-grader and the juice wasextracted using a screw press. The collected juice was heated for 10seconds at 110° C., and ascorbic acid was added to a concentration ofabout 100 mg %, thus obtaining a crude cabbage juice with a pH of 6.0.

(2) A citric acid solution was added to the crude cabbage juice thusobtained to adjust the pH to 4.0. In this instance, the amount of citricacid solution used was 1000 l for 2.6 kg of the juice. After theaddition of Pectinase SS™ (manufactured by Yakult PharmaceuticalIndustry Co., Ltd.) to make a concentration of 0.05%, an enzymaticreaction was carried out at 45° C. for one hour. After the enzymaticreaction, the resultant mixture was heated at 95° C. for 10 seconds,quenched, and centrifuged in a DeLaval centrifugal separator to removesuspensions. Because the resulting liquor was slightly opaque, theliquor was filtered through #500 kieselguhr, then #200 kieselguhr, andconcentrated under vacuum to 30° Bx.

(3) The concentrated vegetable juice was diluted to 15 Bx to obtain avegetable juice for treatment (ascorbic acid concentration: 295 mg %, pH3.95).

2000 l of this juice was run through the IRA-94S™ column, which waspreviously treated with an organic acid and washed with water (resinvolume: 1000 l, resin pH 2.83, acid degree of citric acid: 0.07%) in thesame manner as in Example 1 (3), by a downward countercurrent flow, at aspace velocity of SV=10 and a flow rate of 1000 l/6 minutes. To avoiddilution of the vegetable juice when switching to water, vegetable juicecollected during 5 minutes from the start of elution and 5 minutes fromthe start of water feeding after the treatment was discharged.

1940 l of vegetable juice at 14.2° Bx and 4.3 pH was thus obtained.

The IRA-94S™ column was regenerated and washed in the same manner as inExample 1 (6).

Comparative Example 1

(1) The core of a cabbage was removed and the cabbage was cut with acutter crosswise into four equal fractions. The leaves of the cabbagewere separated and washed with a detergent suitable for food use. Afterrinsing with water, the leaves were treated with hot water to heat thecenter of thickest ribs to 85° C.

The leaves were then crushed using a micro-grader and juice wasextracted using a screw press. The collected juice was heated for 10seconds at 110° C., and ascorbic acid was added to a concentration ofabout 100 mg %, thus obtaining a crude cabbage juice with a pH of 5.9.

(2) After the addition of Pectinase SS™ (manufactured by YakultPharmaceutical Industry Co., Ltd.) to make a concentration of 0.05%, anenzymatic reaction was carried out at 45° C. for one hour. After theenzymatic reaction, the resultant mixture was heated at 95° C. for 10seconds, cooled, and centrifuged in a DeLaval centrifugal separator toremove suspensions.

The resulting liquor was filtered through #500 kieselguhr, then #200kieselguhr, and concentrated to 30 Bx. The properties of theconcentrated vegetable juice were 30.2 Bx, the acid degree of citricacid: 0.32%, and 5.1 pH.

Comparative Example 2

(1) The vegetable juice obtained in the Comparative Example 1 wasdiluted to 15 Bx to obtain a vegetable juice for treatment (ascorbicacid content: 293 mg %, pH 5.2).

(2) To 1000 ml of this vegetable juice was added 600 ml of the resinIRA-94S™ regenerated and washed in same manner as in Example 1(6). Themixture was gently stirred for 10 minutes and the resin was separatedusing an 80 mesh filter. The juice obtained had a pH of 9.8 and the odorof ammonia, and was unacceptable as a drink.

Comparative Example 3

(1) The concentrated vegetable juice obtained in the Comparative Example1 was diluted to 15° Bx and 20% citric acid solution was added to adjustthe pH to 4.0.

(2) To 1000 ml of this vegetable juice was added 600 ml of the resinIRA-94S™ regenerated and washed in same manner as in Example 1 (6). Themixture was gently stirred for 10 minutes and the resin was separatedusing an 80 mesh filter. The cabbage juice obtained had the propertiesof 11.8 Bx and 7.2 pH.

Comparative Example 4

(1) The concentrated vegetable juice obtained in the Comparative Example1 was diluted to 15 Bx and 20% citric acid solution was added to adjustthe pH to 4.0.

(2) 1000 ml of this juice was treated with the regenerated IRA-94S™column (resin volume 500 ml) by downward countercurrent flow. Theinitial fraction of the juice had a strong odor of ammonia and was thusdiscarded. However, the following fractions continued to have anammonium odor and could not be used as a drink.

Evaluation Example 1

(1) The undiluted vegetable juices (original) prepared in Example 1-3,Comparative Example 1, and Comparative Example 3 were adjusted to aconcentration of 30% (converted to 1.5 Bx) and citric acid was added tomake 4.0 pH. 100 ml of each juice was hot packed into a bottle andsubjected to composition analysis. The results are shown in Table 1.

                  TABLE 1    ______________________________________                             Comparative              Example        Example              1      2      3        1    3    ______________________________________    Bx          1.5      1.5    1.6    1.6  1.5    pH          3.98     3.99   3.98   3.99 4.00    Ascorbic    16.3     16.2   15.8   16.4 14.5    acid (mg %)    Amine-type  24.4     24.2   22.1   24.7 20.2    nitrogen (mg %)    ______________________________________

Evaluation Example 2

The ascorbic acid concentration of each vegetable juice used in theEvaluation Example 1 was adjusted to 20 mg %. The juice was then hotpacked.

The juices produced on the same day and stored for a prescribed numberof days at 37° C. after production were cooled and subjected to.anorganoleptic test.

The organoleptic test was carried out by nine panelists, all beingresearchers working in the development of fruit juices, to evaluated thepresence or absence of 1 cabbage odor, 2 unordinary stench (stench ofpickles or rotten pickles; the panelists smelled a similar odorbeforehand for training), and 3 resin odor (stench of amine; thepanelists smelled an odor of fresh IRA-94S beforehand for training). Theresults of the organoleptic test were rated according to the followingstandard.

The odor of cabbage, unordinary stench, and resin odor on the same dayon which the vegetable juice was prepared are shown in Table 2, and theodor of cabbage and the unordinary stench of the juice stored at 37° C.for four weeks and eight weeks are shown in Table 3.

Evaluation standard

Score:

0: There was no odor at all.

1: An odor was identified only with difficulty.

2: A very slight odor was sensed.

3: A slight odor was sensed.

4: The odor is significant.

5: The odor was strong.

                  TABLE 2    ______________________________________              The same day on which juice was prepared.                        Unordinary              Cabbage odor                        stench     Resin odor    ______________________________________    Example 1   3.0         0.7        0.5    Example 2   2.6         0.6        0.5    Example 3   3.2         0.8        0.8    Comparative Ex. 1                3.8         1.5        0.5    Comparative Ex. 3                3.2         1.1        3.0    ______________________________________

                  TABLE 3    ______________________________________             After 4 weeks at 37° C.                          After 8 weeks at 37° C.             Cabbage                    Unordinary                              Cabbage  Unordinary             odor   stench    odor     stench    ______________________________________    Example 1  3.1      1.0       3.2    1.7    Example 2  2.3      0.8       2.7    1.5    Example 3  3.5      1.2       3.5    2.0    Comparative Ex. 1               4.0      3.6       4.1    4.3    Comparative Ex. 3               3.6      1.3       3.6    2.0    ______________________________________

As clear from the Evaluation Examples 1 and 2, the vegetable juice ofthe present invention produced almost no unordinary bad odor afterstorage at 37° C. in spite of the fact that there was almost nodifference in the composition of the juice of the present invention andthat prepared by a conventional process. In addition, the vegetablejuices of the Examples 1-3 were completely free from a resin odor whichwas possessed by the juice prepared in the Comparative Example 3.

Industrial Applicability

The process of the present invention prevents production of anunordinary bad odor like a pickle stench in vegetable juice when thejuice is stored at ordinary temperatures. The process thus has made itpossible for a variety of vegetable juices such as cabbage juice andbroccoli juice, which have not been provided as commercial productsheretofore, to be served as drinks which can be stored at ordinarytemperatures. This has been achieved by preventing the vegetable juicefrom being contaminated by a resin odor, incorporation of which has beenunavoidable in the conventional process for manufacturing vegetablejuice, by means of a special method comprising contacting a weakly basicanion exchange resin with an organic acid.

The process of the present invention thus provides a convenient new typeof vegetable drink with a natural flavor and desirable form from theaspect of food hygiene. These effects are significant in the foodindustry.

We claim:
 1. A process for preparing storable vegetable juice comprisingcrushing vegetables selected from the group consisting of cabbage,broccoli, brussels sprouts, cauliflower, kohlrabi, radish, onion andeggplant to extract juice, adding an organic acid to the vegetablejuice, separately absorbing an organic acid onto a weakly basic anionexchange resin, then washing the resin with water until the pH ofwashing effluent is 2.6 or more, thereby removing amine compounds fromthe resin and treating said acidified juice with the washed resin. 2.The process for preparing storable vegetable juice according to claim 1,wherein the weakly basic anion exchange resin on which an organic acidhas been adsorbed is prepared by causing a weakly basic anion exchangeresin to adsorb an organic acid and washing the resulting resin withwater until the acidity of the effluent water is reduced to 0.2% orbelow.
 3. The process for preparing storable vegetable juice accordingto claim 1, wherein the weakly basic anion exchange resin on which anorganic acid has been adsorbed is used in an amount of 10 to 100 partsfor 100 parts of the extracted vegetable juice.
 4. The process forpreparing storable vegetable juice according to claim 1, wherein the pHof the vegetable juice after the addition of an organic acid is higherthan the pH of the resin.
 5. The process for preparing storablevegetable juice according to claim 1, further comprising at least onetreatment to make the juice more transparent.
 6. The process forpreparing storable vegetable juice according to claim 1, furthercomprising a step of adding cyclodextrin.
 7. A food containing avegetable juice prepared by the process defined in claim 1.